Electric-motor controller.



T. VARNEY.

ELECTRIC MOTOR CONTROLLER.

APPLICATTON FILED SEPT. 18. SH.

1 ,164,038, Patented Dec. 14, 1915.

2 SHEETS-SHEET l.

WITNESSES: INVENTOR ATTORNEY COLUMBIA PLANOURAPH CO..WA5HINOTON,.D. C.

T. VARNEY.

ELECTRIC MOTOR CONTROLLER.

APPLICATION FILED SEPT. 18, I91 I.

1 ,164,038. Patented Dec. 14, 1915.

2 SHEETS-SHEET 2.

Ely. Z. 4

WITNESSES: i /TNVENTOR W ATTORNEY UNITED STATES PATENT OFFICE.

THEODORE VARNEY, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR T0 WESTINGHOUSEELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

ELECTRIC-MOTOR CONTROLLER.

Application filed September 18, 1911.

To all whom it may concern:

Be it known that I, THEODORE VARNEY, a citizen of the United States, anda resident of Pittsburgh, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement in Electric-Motor Controllers, of which the following is a specification.

My invention relates to control systems for electric motors and it hasspecial reference tosuch systems as embody electric motor-operatedswitching devices for governing the main motor circuits.

The object of my invention is to provide a controller of the class aboveindicated hav ing a pilot motor which is responsive in speed to .thecurrent traversing the main motor circuit.

Broadly considered, my invention consists of a motor-operated controllerfor electric motors, the pilot motor of which is dependent, for thespeed of its operation, upon the current traversing the circuit of themain motor.

I do not wish to be limited to any particular type of controller, but myinvention is well adapted for use with a controller of the unit switchtype comprising a motor-op erated master controller which is delayed inits action in accordance with the current traversing the main motorcircuit.

Figure 1 of the accompanying drawings, is a diagrammatic view of acontrol system embodying my invention. Fig. 2 is a View corresponding toFig. 1 of a slightly modified arrangement which also embodies myinvention, and Fig. 3 is a. sectional elevation,

on a larger scale, of the master controller and its driving motor, showndiagrammati- Cally in Fig. 2.

Referring to Fig. 1 of the drawings, the system here shown comprises amotor having an armature 1 and a field magnet winding 2 which issupplied with energy from any suitable source, through conductors 3 and4, a resistor composed of sections 5, 6. 7', 8 and 9, which may bereplaced by any suitable voltage-adjusting means, resistance-controllingswitches 10, 11, 12, 13' and 14, a master switch 15, a small drivingmotor 16 therefor, hereinafter called the pilot motor, manually operatedswitching devices 17 and 18 and a line switch 19-.

The switch 18 is preferably an ordinary push button switch which isnormally held Specification of Letters Patent.

Patented Dec. 14, 1915.

Serial No. 649,915.

closed, and the switch 17 is provided with a magnetizable armature 20and a holding coil 21, into the field of which the armature 20 is movedwhen the switch is adjusted from its normal position a to its positionb.

The pilot motor 16 comprises an armature 22, a field magnet winding 23which is either connected directly in series with the main motor circuitor in a circuit derived therefrom.

The master controller 15 comprises a 1'0- tatively adjustable arm 24:,which is geared to the armature of the motor 16 and a plurality ofcontact members 25, 26, 27, 28 and 29 with which the arm is adapted toengage in the order named.

The operation of and the circuit ME?- tions for the system are asfollows: Assum ing that the switches and controlling devices occupy thepositions shown in the drawings, if the switch 17 is moved from itsposition a to position b, a circuitwill be completed from line conductor3, through conductor 30 and auxiliary resistor 31, which is intended toreduce the voltage on the control circuits and may be omitted ifdesired, conductor 32, contact terminals 33 and 31 of switch 17,conductor 35, push button switch 18 and coil 36 of the switch 19 toopposite line conductor 1. The coil 36, when energized, closes theswitch 19 and completes the motor circuit from conductor 3, throughconductor 30, coil 21, conductor 37, switch 19, armature 1, field magnetwinding 2, resistor sections 5 to 9, inclusive, conductor 38, fieldmagnet winding 23 of motor 16 which may or may not be paralleled byshunt 39 and conductor 10 to line conductor 4:. It thus appears that thecoil 21 is energized so that it holds the switch 17 in position b, andthe motor is connected across the circuit in series with the resistorsections. Furthermore, a control circuit is established from conductor35, through a limit switch 11 of the master switch 15, conductor 12,armature 22 of the motor 16, conductor 43, and contact members 14 and415 of switch 17 to line conductor 4.

It is evident that the field of the motor 16 will be strongly energizedwhen the switch 19 is first closed and, consequently, its speed is veryslow until the large motor has accelerated somewhat and the currenttraversing the motor circuit has become materially reduced. The rotationof the small motor produces a counterclockwise movement of the contactarm 24 into engagement with the contact member 25. The first eiiect ofthis movement is to permit the limit switch 16 to close. The engagementof the arm with contact member 25 completes a control circuit fromconductor 30, through resistor 31., arm contact 25, conductor at? andcoil 48 of switch 10, to line conductor l. The switch 10, when closed,short circuits section 5 of the resistor which produces an accelerationof the main motor and temporarily slows down the motor 16 by reason ofthe increased current following the application of the higher Voltagetothe main motor terminals.

t is evident that the motor 16 may be so lesigned as to introduce atime-element between the steps of the acceleration according to thecurrent traversing the motor circuit. (lonseouently. it the motor isunder a liQ'ht load, the acceleration will be effected quickly while, itit is started under a heavy load, the acceleration will be effectedslowly. One of the great advantages in the arrangement of my intentionlies in the tact that the motor will, in any case, be accelerated, sincethe pilot motor will. always operate, although its operation may beslow. The action of the pilot motor is repeated for each step as the arm2% successively engages the contact members 26, 27, 28 and 29 and as theresistor sections 6, 7, 8 and 9 are successively short circuited.Finally, when the arm 2-L reaches the end of its travel, the limitswitch 41 will be opened by an actuating pawl 4. 9 and the pilot motorcircuit which was completed through it will be interrupted. If it isdesired to bring the main motor to rest, it is only necessary totemporarily open the push button switch 18, which will deenergiiie thecoil causing the switch 19 to interrupt the ma n motor circuit and todei nergize coil 21. The switch 17 is thus permitted to fall to positiona, and the push button may be released with-out causing the motor to bere-accelerated.

As soon as the switch 17 mo es into position a. the pilot motor ci cuitis established from conductor 30, through resistor 3 conductor con actme bers 33 and 50, conductor 51. limit switch 46, conductor 43. armature22. conductor 42 and contacts'52 and 43 to line conductor 4. The pilotmotor armature will thus be supplied with energy which will prod ce a cockwise rotation of the a m 24 wh ch will be com a ati ely ra id sincethe mo o is then oneratin under a ery weal: fie dv due to its residual mnet sm. .l n auxiliar shunt or series field magnet winding may beprovided, if desired. fo the purpose of gi ing the pilot motor a fieldwhich is independent of the main motor circu t.

Pefe ring to riots. and 3 of the drawin'gs, the system here shown issimilar to the system of Fig. 1, like parts being designated by the samereference characters, except that the pilot motor is arranged to operatein only one direction, a magnetic clutch being introduced between themotor and the arm of the controller, in order to permit the arm to bequickly retracted to its oit position in case the line voltage shouldfail temporarily or when it is desired to bring the main motor to rest.

As shown in Fig. 3, the arm 24 together with the magnetizable plate ordisk 53, is attached to the outer end of a stud or bolt 5% which extentsloosely through a mag netizable cylindrical. member The member isrotatively mounted in a hollow cylindrical bracket or hearing 56 whichis attached to an insulating slab or face plate 57 on which the contactmembers 25 to 29 of the controller are mounted. The rear end of themember is provided with a tlange in which gear teeth are cut tocooperate with a gear 58 which is mounted on the shaft of the motor 16.TJithin the hollow cylindrical member 55 and around the stud 54; is acoil which, when energized, attracts the magnetizable plate or disk 53to the front end of the member 55, making the two members operatetogether. Since the arm 2% is secured to the disk a rotatire movement ofthe arm will be effected when the motor is in operation and the coil 59is energized.

The operation of the system shown in Fig. 2 is as follows: It a pushbutton switch 60, which is normally open, is temporarily closed,assuming that the switches and control mechanisms occupy the positionsshown in Fig. 2, a circuit will be established from conductor 3, throughconductor 30, resistor 31, push button switch 60 limit switch ll andmotor armature 22 to opposite line conductor l. Another circuit will beestablished from push button switch 60 through conductor 35 and coil 36of switch 19 to conductor 4. The switch 19 will be closed and the mainmotor circuit will be established from conductor 3 through a holdingcoil (31 which renders the position of the swtich 19 independent of thecoil 36, switch 19, armature l and field magnet winding 2, resistorsections 5 to 8, inclusive, conductor 38 and field magnet winding 23 ofmotor 16 to line conductor 42.

Since the holding coil 61 is connected in series with the motor circuit,the switch 19 will remain closed and it is only necessary to hold thepush button switch (50 closed for a very short time in order to have themotor accelerated automatically.

The pilot motor 16 will be started as soon as the circuits above tracedare completed, but the coil 59, which operates the clutch and couplesthe arm 2t to the motor arma ture, is not energizeduntil the switch 19is closed, circuit then being completed from conductor 30, throughresistor 31, coil 59, conductor 63, contacts 64 of switch 19 toconductor 4. Following the energizing of coil 59, the arm will berotated in a counterclockwise direction in opposition to a spring 62,the speed of the motor being varied, as already described in connectionwith the system of Fig. 1, by reason of the fluctuations ,in the currenttraversing the main motor circuit. As the arm is moved successively intoengagement with contact members 25, 26, 27 and 28, theswitches 10, 11,12 and 13 will be closed and the resistor sections 5, 6, 7 and 8 shortcircuited. Finally the limit switch 41 will be opened as before, and thepilot motor will be brought to rest.

In order to prevent the spring 62 from overhauling the motor 16 when theclutch is energized and the motor circuit is interrupted, (by the limitswitch 41, for example) it will probably be of advantage to substitute aworm and wheel for the spur gearing between the clutch member 55 and themotor shaft.

W'ith the arrangement shown, the spring 62 should not be suflicientlystrong to overhaul the motor and, consequently, the arm will remain inengagement with the contact 28 until the clutch is released by thedeenergizing of coil 59. This will be accomplished automatically in casethe line voltage falls automatically, since the switch 19 will be openedand the control circuit, through contacts 64, interrupted. A push buttonswitch 65, which is normally closed, may preferably be inserted in thecircuit traced, through conductor 63 in order to permit the sections ofthe resistors to be re-inserted, if desired.

It is evident that the arm 24! and the contact segments cooperatingtherewith may be utilized to govern the main motor circuit directly andthat other variations in arrangement and circuit connections may beeffected within the spirit and scope of my invention.

I claim as my invention:

1. A control system comprising a main motor, a resistor, means forgradually excluding the resistor from the circuit to accelerate themotor and a pilot motor for operating said means, the speed of saidpilot motor being varied inversely as the current traversing the mainmotor circuit varies.

2. A control system comprising a main motor, an accelerating resistortherefor, a controller for gradually excluding the resistor from thecircuit, said controller comprising a plurality of stationarv contactmembers and a movable member adapted to sweep over the stationarymembers, and means for actuating said movable member to graduallyexclude the resistor at a speed that varies inversely as the currenttraversing the main motor circuit varies.

3. A control system comprising a main motor, an accelerating resistortherefor, a controller for gradually excluding the resistor from thecircuit, said controller comprising a plurality of stationary contactmembers and a movable member adapted to sweep over the stationarymembers, means for actuating said movable member at a speed that variesinversely with the current traversing the motor circuit, said meanscomprising a pilot motor having a single field magnet winding in serieswith the main motor.

4. A control system comprising a main motor, a resistor, a plurality ofindependently operated switches for short circuiting the resistor insections, a controller for producing a sequential operation of the shortcircuiting switches and means for actuating the controller at a speedthat varies inversely as the current traversing the main motor circuitduring the acceleration of the main motor varies.

5. A control system comprising a main motor, a resistor, a plurality ofindependently operated switches for short circuiting the resistor insections, a controller for producing a sequential operation of the shortcircuiting switches, a pilot motor for operating the controller soarranged that it automatically varies the speed of said controllerinversely as the current traversing the main motor circuit during theacceleration of the main motor varies.

6. A control system comprising a main motor, a resistor, a plurality ofindependently operated switches for short circuiting the resistor insections, a controller for producing a sequential operation of the shortcircuiting switches, and means for actuating said controller at a speedthat varies inversely with the current traversing the main motorcircuit, said means comprising a pilot .motor having a field magnetwinding that is in circuit with said main motor.

7 A system of control comprising a main motor, a resistor and acontroller for gradually short circuiting the resistor, said controllercomprising a plurality of stationary contact members and a movablecontact member adapted to sweep over the stationary members and meanstending to return the movable member to its off position, a pilot motorfor operating the movable member, and a clutch between the pilot motorand the movable member which is actuated only when current is suppliedto the main motor, said pilot motor being responsive to the currenttraversing the main motor clrcuit.

A control system comprising a motor, a resistor, a controller forgradually short circuiting the resistor, a pilot motor for actuatingsaid controller at a rate Varying insubscribed my name this 12th day ofSepversely wlth the current traverslng the main tember, 1911. motoro1rou1t, and means compnsmg an elec- T T tronmgnetic clutch forcontrolling the opera- THEODORE VARLEX' atire connection of said pilotmotor to said Witnesses: controller. D. H. MACE,

In testimony whereof, I have hereunto B. B HINES.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. C.

